1. Field of the Invention
The present invention relates to a polishing composition, a method for manufacturing a substrate with the polishing composition, a method for polishing a substrate to be polished with the polishing composition, a process for reducing fine scratches of a substrate with the polishing composition, and a process for accelerating polishing of a magnetic disk substrate with the polishing composition.
2. Discussion of the Related Art
Recent memory hard disk drives have been demanded to have high areal density and small diameter. In order to increase the areal density, it has been strongly urged to lower flying height and to reduce the unit area of recording. Along with this trend, the surface quality required after polishing has become severely assessed every year even in a method for manufacturing a magnetic disk substrate. In order to meet the requirement of the low flying height, the disk surface is required to have reduced surface roughness, waviness, roll-off, and projections. In order to meet the requirement of the reduction of the unit area of recording, sizes and depth of permitted scratches and pits have become increasingly small.
Also, in the field of semiconductors, the trends of producing thinner wiring have been progressed along with the trends of highly integrated circuits and higher speed at the operating frequencies. Even in the method for manufacturing a semiconductor device, since the focal depth becomes shallow with the trend of thinning the wiring during the exposure of a photoresist, further smoothening of a pattern-forming surface has been desired.
In order to realize the surface quality described above in consideration of productivity, there has been proposed a process for increasing a polishing rate, wherein a colloidal silica is used as an abrasive to realize good surface quality, and various additives are added thereto (Japanese Patent Laid-Open Nos. Hei 11-246849 and 2000-42904). However, any of these methods do not achieve a satisfactory polishing rate.
Japanese Patent Laid-Open Nos. Hei 9-204657, Hei 10-226784, Hei 10-265766, and Hei 9-208934 each discloses the use of phosphonic acid in a polishing composition. However, the phosphonic acid used in these polishing compositions is used as a stabilizer for decomposition of an oxidizing agent such as hydrogen paroxide, or as a gelation inhibitor in a case where fumed silica is used. Therefore, effects of realizing high-quality surface and increasing polishing rate have not been known in these polishing compositions.
In addition, recently, as new surface defects, fine scratches having depth of 0.1 nm or more and less than 5 nm, a width of 10 xcexcm or more and less than 50 xcexcm, and a length of 10 xcexcm or more and less than 1 mm have been found. When the fine scratches are reduced from the substrate, there are expected that excellent effects of stabilization of lowered flying height and reduction of missing pulse error are exhibited. However, in the conventional methods, the fine scratches could not be sufficiently reduced.
An object of the present invention is to provide a polishing composition used in final polishing of memory hard disk and polishing for semiconductor elements, having small surface roughness of a substrate after polishing, and being capable of polishing at a high speed economically for a long period of time, without generating surface defects such as projections and polishing scratches; a method for manufacturing a substrate with the polishing composition; a method for polishing a substrate to be polished with the polishing composition; a process for reducing fine scratches of a substrate; and a process for accelerating polishing of a magnetic disk substrate with the polishing composition.
These and other objects of the present invention will be apparent from the following description.
According to the present invention, there are provided:
[1] a polishing composition comprising an abrasive, an oxidizing agent, a polishing accelerator, and water, wherein the polishing accelerator comprises an organic phosphonic acid;
[2] a method for manufacturing a substrate, comprising polishing a substrate to be polished with the polishing composition of item [1];
[3] a method for polishing a substrate comprising polishing a substrate to be polished with the polishing composition of item [1];
[4] a process for reducing fine scratches of a substrate, comprising polishing a substrate to be polished with the polishing composition of item [1]; and
[5] a process for accelerating polishing of a magnetic disk substrate, comprising applying the polishing composition of item [1] to a magnetic disk substrate to be polished.